Use groups of 3.Materials: 15 index cards, watch with a second hand, paper

Racing Ratios

Copy the ratios listed below onto index cards, one per card. Shuffle the cards. Lay the cards face down in a stack on the table. Each student should have a sheet of notebook paper. Decide who will be player 1, player 2, and player 3. In the first round, player 1 will be the timekeeper. Begin by flipping over the first card. Players 2 and 3 then write down as many different ratios that are equal to the ratio on the card as they can in one minute. When one minute is up, players 2 and 3 will take turns calling out each ratio they have listed, crossing off identical answers and circling those that are unique. Each unique answer is worth one point. The timekeeper should verify that the players' answers are in fact equivalent to the original ratio.

Ratios to put on cards:

2 to 4

6 to 18

4 to 28

6 to 9

5 to 15

5 to 40

14 to 21

7 to 35

1 to 8

3 to 27

10 to 30

2 to 16

6 to 24

21 to 24

7 to 8

Continue taking turns as the timekeeper and play until all cards are used. The player with the most points at the end of the game wins.